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<head><meta charset="utf-8"><title>meeting 2021-06-15 · project-const-generics · Zulip Chat Archive</title></head>
<h2>Stream: <a href="https://rust-lang.github.io/zulip_archive/stream/260443-project-const-generics/index.html">project-const-generics</a></h2>
<h3>Topic: <a href="https://rust-lang.github.io/zulip_archive/stream/260443-project-const-generics/topic/meeting.202021-06-15.html">meeting 2021-06-15</a></h3>

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<a name="242743563"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/260443-project-const-generics/topic/meeting%202021-06-15/near/242743563" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/260443-project-const-generics/topic/meeting.202021-06-15.html#242743563">(Jun 15 2021 at 14:46)</a>:</h4>
<p>I'm around today :)</p>



<a name="242743602"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/260443-project-const-generics/topic/meeting%202021-06-15/near/242743602" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/260443-project-const-generics/topic/meeting.202021-06-15.html#242743602">(Jun 15 2021 at 14:46)</a>:</h4>
<p>though I'm very much playing catch up this week</p>



<a name="242744650"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/260443-project-const-generics/topic/meeting%202021-06-15/near/242744650" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Boxy [she/her] <a href="https://rust-lang.github.io/zulip_archive/stream/260443-project-const-generics/topic/meeting.202021-06-15.html#242744650">(Jun 15 2021 at 14:52)</a>:</h4>
<p><span aria-label="wave" class="emoji emoji-1f44b" role="img" title="wave">:wave:</span> <span class="user-mention" data-user-id="116009">@nikomatsakis</span></p>



<a name="242744685"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/260443-project-const-generics/topic/meeting%202021-06-15/near/242744685" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Boxy [she/her] <a href="https://rust-lang.github.io/zulip_archive/stream/260443-project-const-generics/topic/meeting.202021-06-15.html#242744685">(Jun 15 2021 at 14:53)</a>:</h4>
<p>not much has happend const generics wise last week ^^</p>



<a name="242744801"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/260443-project-const-generics/topic/meeting%202021-06-15/near/242744801" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/260443-project-const-generics/topic/meeting.202021-06-15.html#242744801">(Jun 15 2021 at 14:53)</a>:</h4>
<p>One thing that I wanted to do this month, I remember, is to rpepare a kind of write-up of the equality discussion we had</p>



<a name="242744993"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/260443-project-const-generics/topic/meeting%202021-06-15/near/242744993" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/260443-project-const-generics/topic/meeting.202021-06-15.html#242744993">(Jun 15 2021 at 14:54)</a>:</h4>
<p>Oh heh I was supposed to do that by today</p>



<a name="242745043"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/260443-project-const-generics/topic/meeting%202021-06-15/near/242745043" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/260443-project-const-generics/topic/meeting.202021-06-15.html#242745043">(Jun 15 2021 at 14:54)</a>:</h4>
<p>I guess we could put a bit of time into it</p>



<a name="242745179"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/260443-project-const-generics/topic/meeting%202021-06-15/near/242745179" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/260443-project-const-generics/topic/meeting.202021-06-15.html#242745179">(Jun 15 2021 at 14:54)</a>:</h4>
<p>The idea was to have the notes ready for a lang team meeting <a href="https://github.com/rust-lang/lang-team/issues/94">https://github.com/rust-lang/lang-team/issues/94</a></p>



<a name="242745220"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/260443-project-const-generics/topic/meeting%202021-06-15/near/242745220" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/260443-project-const-generics/topic/meeting.202021-06-15.html#242745220">(Jun 15 2021 at 14:54)</a>:</h4>
<p>I may have overcomitted slightly :)</p>



<a name="242745273"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/260443-project-const-generics/topic/meeting%202021-06-15/near/242745273" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/260443-project-const-generics/topic/meeting.202021-06-15.html#242745273">(Jun 15 2021 at 14:55)</a>:</h4>
<p>Maybe best to acknowledge that this won't happen and kick it until next month</p>



<a name="242745285"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/260443-project-const-generics/topic/meeting%202021-06-15/near/242745285" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/260443-project-const-generics/topic/meeting.202021-06-15.html#242745285">(Jun 15 2021 at 14:55)</a>:</h4>
<p>but probably still worth investing a bit of energy</p>



<a name="242745303"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/260443-project-const-generics/topic/meeting%202021-06-15/near/242745303" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/260443-project-const-generics/topic/meeting.202021-06-15.html#242745303">(Jun 15 2021 at 14:55)</a>:</h4>
<p>Is it just me and you, <span class="user-mention" data-user-id="326176">@Boxy [she/her]</span> ?</p>



<a name="242745319"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/260443-project-const-generics/topic/meeting%202021-06-15/near/242745319" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/260443-project-const-generics/topic/meeting.202021-06-15.html#242745319">(Jun 15 2021 at 14:55)</a>:</h4>
<p>I guess you don't know :)</p>



<a name="242745335"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/260443-project-const-generics/topic/meeting%202021-06-15/near/242745335" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/260443-project-const-generics/topic/meeting.202021-06-15.html#242745335">(Jun 15 2021 at 14:55)</a>:</h4>
<p>Who else is around?</p>



<a name="242745344"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/260443-project-const-generics/topic/meeting%202021-06-15/near/242745344" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Boxy [she/her] <a href="https://rust-lang.github.io/zulip_archive/stream/260443-project-const-generics/topic/meeting.202021-06-15.html#242745344">(Jun 15 2021 at 14:55)</a>:</h4>
<p>i know that lcnr isnt around</p>



<a name="242745459"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/260443-project-const-generics/topic/meeting%202021-06-15/near/242745459" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/260443-project-const-generics/topic/meeting.202021-06-15.html#242745459">(Jun 15 2021 at 14:56)</a>:</h4>
<p>so there was <a class="stream-topic" data-stream-id="260443" href="/#narrow/stream/260443-project-const-generics/topic/structural.20equality">#project-const-generics &gt; structural equality</a></p>



<a name="242745479"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/260443-project-const-generics/topic/meeting%202021-06-15/near/242745479" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/260443-project-const-generics/topic/meeting.202021-06-15.html#242745479">(Jun 15 2021 at 14:56)</a>:</h4>
<p>I was sort of planning to scrape some of that thread</p>



<a name="242745490"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/260443-project-const-generics/topic/meeting%202021-06-15/near/242745490" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/260443-project-const-generics/topic/meeting.202021-06-15.html#242745490">(Jun 15 2021 at 14:56)</a>:</h4>
<p>I think we had a hackmd already somewhere</p>



<a name="242745565"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/260443-project-const-generics/topic/meeting%202021-06-15/near/242745565" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Boxy [she/her] <a href="https://rust-lang.github.io/zulip_archive/stream/260443-project-const-generics/topic/meeting.202021-06-15.html#242745565">(Jun 15 2021 at 14:56)</a>:</h4>
<p>there's a hackmd with lcnr's thoughts on how it should work, are you meaning that?</p>



<a name="242745592"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/260443-project-const-generics/topic/meeting%202021-06-15/near/242745592" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Boxy [she/her] <a href="https://rust-lang.github.io/zulip_archive/stream/260443-project-const-generics/topic/meeting.202021-06-15.html#242745592">(Jun 15 2021 at 14:57)</a>:</h4>
<p><a href="https://hackmd.io/-IB2BH1hSWWMQVSfbvVViA">https://hackmd.io/-IB2BH1hSWWMQVSfbvVViA</a></p>



<a name="242745619"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/260443-project-const-generics/topic/meeting%202021-06-15/near/242745619" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/260443-project-const-generics/topic/meeting.202021-06-15.html#242745619">(Jun 15 2021 at 14:57)</a>:</h4>
<p>skimming I found links to two docs</p>



<a name="242745639"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/260443-project-const-generics/topic/meeting%202021-06-15/near/242745639" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/260443-project-const-generics/topic/meeting.202021-06-15.html#242745639">(Jun 15 2021 at 14:57)</a>:</h4>
<ul>
<li><a href="https://hackmd.io/Qvrj_eOFTkCHZrhJ7f1ItA#Patterns">Valtree master plan</a></li>
</ul>



<a name="242745680"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/260443-project-const-generics/topic/meeting%202021-06-15/near/242745680" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/260443-project-const-generics/topic/meeting.202021-06-15.html#242745680">(Jun 15 2021 at 14:57)</a>:</h4>
<ul>
<li><a href="https://hackmd.io/-IB2BH1hSWWMQVSfbvVViA">structural match proposal</a>, which I think was from <span class="user-mention" data-user-id="216206">@lcnr</span></li>
</ul>



<a name="242745719"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/260443-project-const-generics/topic/meeting%202021-06-15/near/242745719" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/260443-project-const-generics/topic/meeting.202021-06-15.html#242745719">(Jun 15 2021 at 14:57)</a>:</h4>
<p>I remember that <span class="user-mention" data-user-id="120791">@RalfJ</span> had a plan, too</p>



<a name="242745981"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/260443-project-const-generics/topic/meeting%202021-06-15/near/242745981" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/260443-project-const-generics/topic/meeting.202021-06-15.html#242745981">(Jun 15 2021 at 14:58)</a>:</h4>
<p>I know there are some writeups of Ralf's plan on a github issue</p>



<a name="242746015"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/260443-project-const-generics/topic/meeting%202021-06-15/near/242746015" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/260443-project-const-generics/topic/meeting.202021-06-15.html#242746015">(Jun 15 2021 at 14:58)</a>:</h4>
<p>I found <a href="#narrow/stream/260443-project-const-generics/topic/structural.20equality/near/239274444">this comment</a> that seems key</p>



<a name="242746135"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/260443-project-const-generics/topic/meeting%202021-06-15/near/242746135" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/260443-project-const-generics/topic/meeting.202021-06-15.html#242746135">(Jun 15 2021 at 14:59)</a>:</h4>
<p><a href="https://github.com/rust-lang/rust/issues/74446#issuecomment-841637790">Ralf's github comment</a></p>



<a name="242746344"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/260443-project-const-generics/topic/meeting%202021-06-15/near/242746344" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/260443-project-const-generics/topic/meeting.202021-06-15.html#242746344">(Jun 15 2021 at 14:59)</a>:</h4>
<p>I'm not 100% clear on the difference between <span class="user-mention silent" data-user-id="216206">lcnr</span>'s proposal and <span class="user-mention silent" data-user-id="120791">RalfJ</span>'s proposal</p>



<a name="242747013"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/260443-project-const-generics/topic/meeting%202021-06-15/near/242747013" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Boxy [she/her] <a href="https://rust-lang.github.io/zulip_archive/stream/260443-project-const-generics/topic/meeting.202021-06-15.html#242747013">(Jun 15 2021 at 15:02)</a>:</h4>
<p>i would need to spend a while re-reading stuff to figure that out <span aria-label="sweat smile" class="emoji emoji-1f605" role="img" title="sweat smile">:sweat_smile:</span></p>



<a name="242747027"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/260443-project-const-generics/topic/meeting%202021-06-15/near/242747027" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/260443-project-const-generics/topic/meeting.202021-06-15.html#242747027">(Jun 15 2021 at 15:02)</a>:</h4>
<p>yeah</p>



<a name="242747032"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/260443-project-const-generics/topic/meeting%202021-06-15/near/242747032" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Boxy [she/her] <a href="https://rust-lang.github.io/zulip_archive/stream/260443-project-const-generics/topic/meeting.202021-06-15.html#242747032">(Jun 15 2021 at 15:02)</a>:</h4>
<p>haven't got a great idea of exactly whats being proposed here</p>



<a name="242747055"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/260443-project-const-generics/topic/meeting%202021-06-15/near/242747055" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/260443-project-const-generics/topic/meeting.202021-06-15.html#242747055">(Jun 15 2021 at 15:02)</a>:</h4>
<p>I was just thinking the same thing</p>



<a name="242747106"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/260443-project-const-generics/topic/meeting%202021-06-15/near/242747106" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/260443-project-const-generics/topic/meeting.202021-06-15.html#242747106">(Jun 15 2021 at 15:03)</a>:</h4>
<p>we don't have a hackmd group, do we</p>



<a name="242747108"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/260443-project-const-generics/topic/meeting%202021-06-15/near/242747108" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/260443-project-const-generics/topic/meeting.202021-06-15.html#242747108">(Jun 15 2021 at 15:03)</a>:</h4>
<p>:)</p>



<a name="242747136"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/260443-project-const-generics/topic/meeting%202021-06-15/near/242747136" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Boxy [she/her] <a href="https://rust-lang.github.io/zulip_archive/stream/260443-project-const-generics/topic/meeting.202021-06-15.html#242747136">(Jun 15 2021 at 15:03)</a>:</h4>
<p>i dont know <span aria-label="sweat smile" class="emoji emoji-1f605" role="img" title="sweat smile">:sweat_smile:</span></p>



<a name="242747256"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/260443-project-const-generics/topic/meeting%202021-06-15/near/242747256" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/260443-project-const-generics/topic/meeting.202021-06-15.html#242747256">(Jun 15 2021 at 15:04)</a>:</h4>
<p>now we do</p>



<a name="242747289"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/260443-project-const-generics/topic/meeting%202021-06-15/near/242747289" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/260443-project-const-generics/topic/meeting.202021-06-15.html#242747289">(Jun 15 2021 at 15:04)</a>:</h4>
<p>and you and I are members :)</p>



<a name="242747308"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/260443-project-const-generics/topic/meeting%202021-06-15/near/242747308" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Boxy [she/her] <a href="https://rust-lang.github.io/zulip_archive/stream/260443-project-const-generics/topic/meeting.202021-06-15.html#242747308">(Jun 15 2021 at 15:04)</a>:</h4>
<p><span aria-label="sparkles" class="emoji emoji-2728" role="img" title="sparkles">:sparkles:</span></p>



<a name="242747361"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/260443-project-const-generics/topic/meeting%202021-06-15/near/242747361" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/260443-project-const-generics/topic/meeting.202021-06-15.html#242747361">(Jun 15 2021 at 15:04)</a>:</h4>
<p>along with some others</p>



<a name="242747428"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/260443-project-const-generics/topic/meeting%202021-06-15/near/242747428" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/260443-project-const-generics/topic/meeting.202021-06-15.html#242747428">(Jun 15 2021 at 15:05)</a>:</h4>
<p><a href="https://hackmd.io/Zrk3iPzOQDC5kOMC1B34_Q">https://hackmd.io/Zrk3iPzOQDC5kOMC1B34_Q</a> &lt;-- structural equality write-up</p>



<a name="242747739"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/260443-project-const-generics/topic/meeting%202021-06-15/near/242747739" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Boxy [she/her] <a href="https://rust-lang.github.io/zulip_archive/stream/260443-project-const-generics/topic/meeting.202021-06-15.html#242747739">(Jun 15 2021 at 15:06)</a>:</h4>
<p>I think it might be helpful to write out what const generics is needing out of "structural equality"</p>



<a name="242747764"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/260443-project-const-generics/topic/meeting%202021-06-15/near/242747764" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/260443-project-const-generics/topic/meeting.202021-06-15.html#242747764">(Jun 15 2021 at 15:06)</a>:</h4>
<p>yes, I'm thinking the same thing</p>



<a name="242747791"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/260443-project-const-generics/topic/meeting%202021-06-15/near/242747791" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/260443-project-const-generics/topic/meeting.202021-06-15.html#242747791">(Jun 15 2021 at 15:07)</a>:</h4>
<p>I was skimming Ralf's comment</p>



<a name="242747794"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/260443-project-const-generics/topic/meeting%202021-06-15/near/242747794" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/260443-project-const-generics/topic/meeting.202021-06-15.html#242747794">(Jun 15 2021 at 15:07)</a>:</h4>
<blockquote>
<p>However, there are 2 things the compiler does where an "unstructured blob" view of a constant is insufficient:</p>
</blockquote>



<a name="242748220"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/260443-project-const-generics/topic/meeting%202021-06-15/near/242748220" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/260443-project-const-generics/topic/meeting.202021-06-15.html#242748220">(Jun 15 2021 at 15:09)</a>:</h4>
<p>I'm just sort of typing random things in there, trying to put together the pieces</p>



<a name="242748404"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/260443-project-const-generics/topic/meeting%202021-06-15/near/242748404" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/260443-project-const-generics/topic/meeting.202021-06-15.html#242748404">(Jun 15 2021 at 15:11)</a>:</h4>
<p>Ralf's write-up is pretty good (as expected)</p>



<a name="242748783"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/260443-project-const-generics/topic/meeting%202021-06-15/near/242748783" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Boxy [she/her] <a href="https://rust-lang.github.io/zulip_archive/stream/260443-project-const-generics/topic/meeting.202021-06-15.html#242748783">(Jun 15 2021 at 15:13)</a>:</h4>
<p>i on the other hand am not great at write-ups <span aria-label="sweat smile" class="emoji emoji-1f605" role="img" title="sweat smile">:sweat_smile:</span></p>



<a name="242749553"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/260443-project-const-generics/topic/meeting%202021-06-15/near/242749553" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/260443-project-const-generics/topic/meeting.202021-06-15.html#242749553">(Jun 15 2021 at 15:18)</a>:</h4>
<p>ok, I finished re-reading ralf's comment</p>



<a name="242749590"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/260443-project-const-generics/topic/meeting%202021-06-15/near/242749590" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/260443-project-const-generics/topic/meeting.202021-06-15.html#242749590">(Jun 15 2021 at 15:18)</a>:</h4>
<p>I can reproduce it, I think, but I think what I'm missing is the <em>counter argument</em> of sorts-- what do we lose in this proposal</p>



<a name="242750032"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/260443-project-const-generics/topic/meeting%202021-06-15/near/242750032" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/260443-project-const-generics/topic/meeting.202021-06-15.html#242750032">(Jun 15 2021 at 15:21)</a>:</h4>
<p>so I guess that omes back to what <span class="user-mention" data-user-id="216206">@lcnr</span>'s counter proposal</p>



<a name="242750053"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/260443-project-const-generics/topic/meeting%202021-06-15/near/242750053" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/260443-project-const-generics/topic/meeting.202021-06-15.html#242750053">(Jun 15 2021 at 15:21)</a>:</h4>
<p>I think we will not have this write-up prepared to be read by today</p>



<a name="242750065"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/260443-project-const-generics/topic/meeting%202021-06-15/near/242750065" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/260443-project-const-generics/topic/meeting.202021-06-15.html#242750065">(Jun 15 2021 at 15:21)</a>:</h4>
<p>but let me put a bit more time into it and identify what I see as some of the gaps</p>



<a name="242750098"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/260443-project-const-generics/topic/meeting%202021-06-15/near/242750098" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/260443-project-const-generics/topic/meeting.202021-06-15.html#242750098">(Jun 15 2021 at 15:21)</a>:</h4>
<p>the other thing that would be good to figure out</p>



<a name="242750144"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/260443-project-const-generics/topic/meeting%202021-06-15/near/242750144" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/260443-project-const-generics/topic/meeting.202021-06-15.html#242750144">(Jun 15 2021 at 15:22)</a>:</h4>
<p>are the constraints and existing behaviors</p>



<a name="242750173"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/260443-project-const-generics/topic/meeting%202021-06-15/near/242750173" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/260443-project-const-generics/topic/meeting.202021-06-15.html#242750173">(Jun 15 2021 at 15:22)</a>:</h4>
<p><span class="user-mention" data-user-id="326176">@Boxy [she/her]</span> did you add this?</p>



<a name="242750175"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/260443-project-const-generics/topic/meeting%202021-06-15/near/242750175" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/260443-project-const-generics/topic/meeting.202021-06-15.html#242750175">(Jun 15 2021 at 15:22)</a>:</h4>
<h3>const eval checked wants:</h3>
<ul>
<li>want to be able to check for equality between constants without evaluating i.e. <code>N + 1</code> and <code>N + 1</code> should be equal, for this to be reasonable we want types of const generics to have a "well behaved" Eq impl</li>
</ul>



<a name="242750183"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/260443-project-const-generics/topic/meeting%202021-06-15/near/242750183" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Boxy [she/her] <a href="https://rust-lang.github.io/zulip_archive/stream/260443-project-const-generics/topic/meeting.202021-06-15.html#242750183">(Jun 15 2021 at 15:22)</a>:</h4>
<p>yea</p>



<a name="242750190"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/260443-project-const-generics/topic/meeting%202021-06-15/near/242750190" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/260443-project-const-generics/topic/meeting.202021-06-15.html#242750190">(Jun 15 2021 at 15:22)</a>:</h4>
<p>what is "const eval checked"? :)</p>



<a name="242750198"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/260443-project-const-generics/topic/meeting%202021-06-15/near/242750198" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Boxy [she/her] <a href="https://rust-lang.github.io/zulip_archive/stream/260443-project-const-generics/topic/meeting.202021-06-15.html#242750198">(Jun 15 2021 at 15:22)</a>:</h4>
<p>oh</p>



<a name="242750214"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/260443-project-const-generics/topic/meeting%202021-06-15/near/242750214" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Boxy [she/her] <a href="https://rust-lang.github.io/zulip_archive/stream/260443-project-const-generics/topic/meeting.202021-06-15.html#242750214">(Jun 15 2021 at 15:22)</a>:</h4>
<p><code>feature(const_evaluatable_checked)</code></p>



<a name="242750232"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/260443-project-const-generics/topic/meeting%202021-06-15/near/242750232" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/260443-project-const-generics/topic/meeting.202021-06-15.html#242750232">(Jun 15 2021 at 15:22)</a>:</h4>
<p>what does that feature do :)</p>



<a name="242750276"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/260443-project-const-generics/topic/meeting%202021-06-15/near/242750276" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Boxy [she/her] <a href="https://rust-lang.github.io/zulip_archive/stream/260443-project-const-generics/topic/meeting.202021-06-15.html#242750276">(Jun 15 2021 at 15:23)</a>:</h4>
<div class="codehilite" data-code-language="Rust"><pre><span></span><code><span class="k">fn</span> <span class="nf">foo</span><span class="o">&lt;</span><span class="k">const</span><span class="w"> </span><span class="n">N</span>: <span class="kt">usize</span><span class="o">&gt;</span><span class="p">()</span><span class="w"> </span>-&gt; <span class="nc">Foo</span><span class="o">&lt;</span><span class="n">N</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="mi">1</span><span class="o">&gt;</span><span class="w"></span>
</code></pre></div>



<a name="242750308"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/260443-project-const-generics/topic/meeting%202021-06-15/near/242750308" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Boxy [she/her] <a href="https://rust-lang.github.io/zulip_archive/stream/260443-project-const-generics/topic/meeting.202021-06-15.html#242750308">(Jun 15 2021 at 15:23)</a>:</h4>
<p>lets you use generic expression as the values for const generics</p>



<a name="242750455"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/260443-project-const-generics/topic/meeting%202021-06-15/near/242750455" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Boxy [she/her] <a href="https://rust-lang.github.io/zulip_archive/stream/260443-project-const-generics/topic/meeting.202021-06-15.html#242750455">(Jun 15 2021 at 15:24)</a>:</h4>
<p>I think it's only tangentially related to valtrees as we don't really have any "value" to do equality on with these</p>



<a name="242750512"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/260443-project-const-generics/topic/meeting%202021-06-15/near/242750512" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/260443-project-const-generics/topic/meeting.202021-06-15.html#242750512">(Jun 15 2021 at 15:24)</a>:</h4>
<p>I think this work, btw, definitely impacts the vision doc</p>



<a name="242750585"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/260443-project-const-generics/topic/meeting%202021-06-15/near/242750585" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/260443-project-const-generics/topic/meeting.202021-06-15.html#242750585">(Jun 15 2021 at 15:25)</a>:</h4>
<p>if nothing else it affects what examples we include there</p>



<a name="242751729"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/260443-project-const-generics/topic/meeting%202021-06-15/near/242751729" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/260443-project-const-generics/topic/meeting.202021-06-15.html#242751729">(Jun 15 2021 at 15:31)</a>:</h4>
<p>ok, I'm going to stop editing for a bit</p>



<a name="242752484"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/260443-project-const-generics/topic/meeting%202021-06-15/near/242752484" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Boxy [she/her] <a href="https://rust-lang.github.io/zulip_archive/stream/260443-project-const-generics/topic/meeting.202021-06-15.html#242752484">(Jun 15 2021 at 15:36)</a>:</h4>
<p>im not sure if the bits about what <code>const_generics</code> and what <code>const_evaluatable_checked</code> want are in the right place or not <span aria-label="thinking" class="emoji emoji-1f914" role="img" title="thinking">:thinking:</span></p>



<hr><p>Last updated: Aug 07 2021 at 22:04 UTC</p>
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